Illicit DischargeEliminationProject
HarrisCounty, Texas
Document No. 070002
PBS&J Job No. 460935
Illicit DischargeEliminationProject
HarrisCounty, Texas
Prepared for:
Harris CountyStorm Water Quality Section
9800 Northwest Freeway, Suite 305
Houston, Texas77092
Prepared by:
PBS&J
1250 Wood Branch Park Drive
Suite 300
Houston, Texas 77079
January 2007
Printed on recycled paper
Contents
Page
Contents
Page
List of Figures...... iv
List of Tables...... v
Executive Summary...... vi
1.0Introduction
2.0DESCRIPTION OF STREAMS AND SAMPLING SITES
2.1BRICKHOUSE GULLY
2.2VOGEL CREEK
3.0STUDY APPROACH
3.1SAMPLING PROGRAM
3.1.1General
3.1.2Dry Weather Discharges from Stormwater System
3.1.3Wastewater Treatment Plants
3.1.4Instream Samples
3.2IDENTIFICATION AND ELIMINATION OF HIGH BACTERIA SOURCES IN STORMWATER SYSTEM
3.2.1Source Identification
3.2.2Source Elimination
3.3STATISTICAL ANALYSIS APPROACH
3.4DISCUSSION
4.0RESULTS
4.1DRY WEATHER DISCHARGES
4.1.1Characterization of Sources
4.1.2Effects of Effort to Eliminate High Bacteria Sources
4.2WASTEWATER TREATMENT PLANTS
4.3INSTREAM – BRICKHOUSE GULLY
4.3.1Before Attempt to Eliminate High Bacteria Sources
4.3.2After Attempt to Eliminate High Bacteria Sources
4.4INSTREAM – VOGEL CREEK
4.4.1Before Attempt to Eliminate High Bacteria Sources
4.4.2After Attempt to Eliminate High Bacteria Sources
5.0DISCUSSION OF RESULTS
5.1INSTREAM WATER QUALITY BEFORE AND AFTER ATTEMPT TO ELIMINATE HIGH BACTERIA SOURCES
5.2COMPARISON OF DRY WEATHER DISCHARGE BACTERIA INPUTS TO MEASURED INSTREAM LEVELS—A CONSISTENCY CHECK
5.3COST OF ELIMINATING HIGH BACTERIA SOURCES
5.4EC TO FC RATIO
5.5WASTEWATER TREATMENT PLANTS
5.5.1Comparison of Bacteria Concentrations at Weir and Outfall
5.5.2Relationship between Effluent EC and Residual Chlorine
6.0CONCLUSIONS AND RECOMMENDATIONS
7.0References
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Contents
Figures, cont’d.
Page
Figures
Page
1Brickhouse Gully Drainage Area......
2Vogel Creek Drainage Area......
3Sources of Dry Weather Discharges that Exceeded EC Single Sample Criterion......
4Relationship Between EC and Total Residual Chlorine at Weir for Plants Sampled......
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Contents
Tables, cont’d.
Page
Tables
Page
1Brickhouse Gully Dry Weather Discharge Data......
2Vogel Creek Dry Weather Discharge Data......
3Sources of Dry Weather Discharges for Brickhouse Gully......
4Sources of Dry Weather Discharges for Vogel Creek......
5Westway WWTP Data......
6Willowood WWTP Data......
7Sunset MHP Data......
8Brickhouse Gully Instream Data (Before Attempt to Eliminate High Bacteria Sources)......
9Brickhouse Gully Instream Data (After Attempt to Eliminate High Bacteria Sources)......
10Vogel Creek Instream Data (Before Attempt to Eliminate High Bacteria Sources)......
11Vogel Creek Instream Data (After Attempt to Eliminate High Bacteria Sources)......
460935/0700021
Executive Summary
Executive Summary
PBS&J was retained by the Harris County Storm Water Quality Section (HCSWQS) to review and document an Illicit Discharge Elimination Project (IDEP). The IDEP was developed and implemented by HCSWQS staff to investigate whether elimination of illicit discharges to urban waterways would measurably reduce instream indicator bacteria levels, and to determine the approximate cost associated with eliminating illicit discharges. Brickhouse Gully and Vogel Creek were selected by HCSWQS for this study.
Brickhouse Gully (Stream Segment 1017A) is a highlyurbanized tributary of White Oak Bayou (Stream Segment 1017). Typical low flow in Brickhouse Gully is in the order of 3 to 5 cubic feet per second (cfs). It was estimated that 20–30% of the low flow was wastewater treatment plant (WWTP) effluent. The sampling site was located at the upstream intersection of Brickhouse Gully and U.S. Highway 290.
Vogel Creek is an improved earthen tributary of White Oak Bayou. HCSWQS measured a dry weather flow rate of 1.76 cfs.It appears that in dry weather the flow in Vogel Creek is predominantly WWTP effluent. The sampling site was at the intersection of Vogel Creek and Breen Drive.
Both streams show high levels of indicator bacteria. Brickhouse Gully is on the 2004 303(d) List of impaired water bodies as not supporting contact recreation use due to bacteria. Vogel Creek is not listed apparently because no assessment was done by the State due to lack of data.
The study involved sampling of dry weather discharges, identification of those with high bacteria concentrations and an attempt at elimination of sources. The Brickhouse Gully site was sampled after the attempt to eliminate high bacteria sources. A historical data set collected by the City of Houston provided the baseline condition. The Vogel Creek site was sampled before and after the attempt to eliminate high bacteria sources. An ancillary study was to investigate the quality of discharges from WWTPs into the study streams. Bacteria and residual chlorine data were collected at the Westway WWTP, Willowood WWTP, and Sunset MHP.
A wide variety of the dry weather discharges were found, including water main leaks, lawn irrigation, air conditioner condensate, groundwater, wash water, and sanitary sewer leaks. Identified sources of sewage were found to be a small proportion of dry weather discharges investigated.Both the flow rate and bacteria level at a particular outfalls appear to be highly variable.
Estimates of bacteria loadings from the dry weather discharge measurements show that dry weather discharges appear to be a major contributor to instream bacteria level in Brickhouse Gully, but relatively minor for Vogel Creek.
Statistical tests comparing mean instream bacteria levels in Brickhouse Gully and Vogel Creek before and after the attempt to eliminate high bacteria sources were conducted.These tests showed a statistical difference in Brickhouse Gully but did not show a statistical difference on Vogel Creek.The result for Brickhouse Gully is not definitive due to the use of different E. Coli (EC) test methods by the City and HCSWQS. Whether or not a statistically significant reduction occurred, the bacteria levels after the elimination attempts were still well in excess of criteria. Moreover, even when dry-weather discharges with high bacteria sources are all eliminated, meeting the EC criteria for contact recreation would likely not be achieved based on the findings in the Luce Bayou Background Study.
A comparison between EC data at the weir and at the outfall of two WWTPs indicates that there was no significant increase in EC concentration in the discharge pipe between the weir and the outfall. The EC concentration at the weir appears to be negatively correlated with total residual chlorine concentration.
Efforts to eliminate dry weather discharges with high bacteria sources should first be focused on streams without substantial dry weather WWTP effluent flow.In this study, the elimination of dry weather sources on Brickhouse Gully, with less than 30% WWTP effluent during dry weather, appeared somewhat successful although the stream standard is still exceeded, whereas, reduction efforts in Vogel Creek, which includes a higher proportion of WWTP effluent, did not appear successful.Due to the inherent high variability of bacteria data, it would be desirable to perform “before and after” instream monitoring on one or two other streams to verify the findings of this study.
With regards to data collection, HCSWQS should consider using the IDEXX method to be consistent with the current norm of EC testing so that data collected by HCSWQS can be compared on an equal basis with data collected by other entities.
460935/0700021
1.0Introduction
PBS&J was retained under Harris County Purchase Order No. PO83016 to review and document two recent projects by the Harris County Storm Water Quality Section (HCSWQS): the Illicit Discharge Elimination Project (IDEP) and the associated Luce Bayou Background Study. The Luce Bayou Background Study is in a separate report. The IDEP was developed and implemented by HCSWQS staff to investigate whether elimination of illicit discharges to urban waterways would measurably reduce instream indicator bacteria levels, and to determine the approximate cost associated with eliminating illicit discharges. PBS&J provided independent professional services to document and comment on the study methods and results.
In 1998 HarrisCounty, the City of Houston, Texas Department of Transportation (TxDOT), and Harris County Flood Control District received a permit from the U.S. Environmental Protection Agency (EPA) to allow the discharge of storm water from the permittees’ storm sewer system into waters of the United States.The permit, called a Municipal Separate Storm Sewer System (MS4) Permit, required permittees to develop a program to locate and eliminate illicit discharges into the MS4.To date, these efforts have included “screening” large storm sewer outfalls for illicit discharges and site visits to sectors of commercial facilities which have been known to present a high potential for discharging pollutants into the MS4.
In 2003, the Texas Clean Rivers Program, administered locally by the Houston-Galveston Area Council (H-GAC), commissioned the Small Watershed Study (PBS&J, 2003) on several small waterways that have high bacteria levels.That study examined the number of illicit discharges to the stream and characterized dry weather discharges.One of the streams in the study was Brickhouse Gully.The study identified 223 potential pollutant sources and 61 discharges in this stream.Eight discharges accounted for a very high percentage of the overall level of bacteria in the stream.The Small Watershed Study did not attempt to identify exact sources of discharges or to eliminate illicit discharges (for example, a source was typically given as a discharge pipe or tributary, rather than the exact source, such as a particular business or a point where a sanitary sewer leaked into a storm sewer).HCSWQS intends to build upon these earlier efforts to locate and eliminate illicit discharges in Brickhouse Gully and Vogel Creek.
The work represents efforts by HCSWQS to eliminate, to the extent practical, illicit discharges along two small streams while characterizing the amount of effort involved in eliminating the discharges and the resulting water quality changes.By understanding the natural baseline for water quality, it can be determined to what level water quality in impaired streams could be improved.In understanding the amount of effort needed to clean up waterways through illicit discharge detection and enforcement, better estimates can be prepared for budgetary and staffing requirements needed to improve water quality to a specified level. An ancillary study was to investigate the quality of discharges from wastewater treatment plants (WWTP) into the study streams.
460935/0700021
2.0DESCRIPTION OF STREAMS AND SAMPLING SITES
2.1BRICKHOUSE GULLY
Brickhouse Gully (Stream Segment 1017A) is a highly-urbanized tributary of White Oak Bayou (Stream Segment 1017) with a drainage area of 11.6 square miles. The drainage area is shown on Figure 1. The following observations have been made by HCSWQS.Most of the stream is a concrete channel.The flow of the stream is approximately 10feet wide and 3inches deep at low flow.The main channel of Brickhouse Gully is approximately 36,600 feet long and has 10 smaller tributaries.Although most of the stream has maintained its major meanders, the water surface itself is generally unshaded.Land use in the contributing drainage area is mostly single-family residential and light industrial (warehousing).Apart from periphyton (small animals and plants that encrust hard substrates), there is little aquatic life in this stream except for occasional pools.In these pools HCSWQS staff reported seeing large numbers of Blue Tilapia (Oreochromis aureus). Brickhouse Gully is on the 2004 303(d) List of impaired waterbodies as not supporting contact recreation use due to bacteria.
U.S. Geological Survey (USGS) gaging station 08074250 (Brickhouse Gully at Costa Rica Street) is located near the confluence of Brickhouse Gully with White Oak Bayou. The gage has a drainage area of 11.4square miles. The gage record starts from September 1, 1964. Unfortunately, there is no discharge record between October 1, 1981 and September 30, 2003 and since February 12, 2004. The following table shows the percentiles of the discharge record for the period between October 1, 2003 and February11, 2004.
Percentile / 0% / 10% / 20% / 30% / 40% / 50% / 60% / 70% / 80% / 90% / 100%Flow (cfs*) / 3.1 / 3.5 / 3.9 / 4.7 / 5.7 / 6.5 / 8.3 / 13.0 / 26.8 / 85.7 / 2010
cfs = cubic feet per second.
Based on this record, it appears that at low flow, the flow in Brickhouse Gully is in the order of 3 to 5 cfs. The City of Houston Westway Wastewater Treatment Plant is located at the headwater of Brickhouse Gully (TPDES NO. 10495-139, permitted at 0.995 million gallons per day [MGD]).Based on the self-reporting data in the Permit Compliance System (PCS) database (EPA, 2006), between July 2003 and June 2006 the monthly discharges of the plant average about 0.56 MGD (0.87 cfs). Therefore, the effluent of the WWTP is 20–30% of the base flow in Brickhouse Gully.
The sampling site for this study was located at the upstream intersection of Brickhouse Gully and U.S. Highway 290 (29° 49 35.44 north, -95° 28 37.28 east). The City of Houston has a well-populated sampling history at this site.
Figure 1, Brickhouse Gully Drainage Area
2.2VOGEL CREEK
Vogel Creek is an improved earthen tributary of White Oak Bayou, with a drainage area of 8.0 square miles in northwest HarrisCounty, just northwest of the City of Houston corporate limits. The drainage area is shown on Figure 2. The following observations have been made by HCSWQS. The main channel of the study area of Vogel Creek is approximately 25,080 feet long and has four smaller tributaries.The land use for this watershed is predominately residential and commercial, with some undeveloped areas.This stream consists primarily of a wet pilot channel punctuated by plunge pools at street crossings until it accepts treated wastewater effluent from Harris County Water Control & Improvement District #133 (Willowood WWTP, TPDES permit No. WQ11153-001, permitted at 3.0 MGD), at which point the stream becomes much deeper and wider.There are occasional pools and runs downstream of the WWTP.The surface of the stream is generally exposed to sunlight, though there are some reaches in which the creek has riparian foliage. There is a great abundance of fish found at the above-mentioned WWTP outfall.The overwhelming majority of these fish are Sailfin molly (Poecillia latipinna), along with (in order of prevalence) Blue tilapia, Rio Grandecichlid (Cichlasoma cyanoguttatum), and Western mosquitofish (Gambusia affinis).In pools downstream of the WWTP large numbers of South American suckermouth armoured catfish were observed.
A second, smaller WWTP (William Donald Smith or Sunset MHP, TPDES permit No. WQ14506-001, permitted at 0.012 MGD) discharges directly into Vogel Creek.
Although HCSWQS has observed high levels of indicator bacteria in this study, Vogel Creek is not on the 303(d) List apparently because no assessment was done by the state due to lack of data.
The sampling site for this study was located at the intersection of Vogel Creek and Breen Drive (29° 53 56.80 north, -95° 28 7.04 east).
Vogel Creek does not have any flow gaging stations. HCSWQS measured the flow rate at the sampling site on June 5, 2006 during base flow at the time of day when data collection was typically done. That flow measurement was 1.76 cfs. From the PCS database (EPA, 2006) between July 2005 and August 2006, the monthly discharges of the Willowood WWTP average about 1.8 MGD (2.8 cfs). The flow measured on the particular date is less than the typical discharge of the Willowood WWTP. It appears that the base flow of Vogel Creek is predominantly WWTP effluent.
Figure 2, Vogel Creek Drainage Area
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3.0STUDY APPROACH
3.1SAMPLING PROGRAM
3.1.1General
Field sampling for all lab-tested parameters and chain-of-custody procedures were conducted according to procedures described in the TNRCC Water Quality Sampling and Shipping Procedures (2002).Analyses of parameters of interest for instream sampling were reported to follow EPA Standard Methods (40 CFR Part 136).Quality control and quality assurance followed those procedures outlined in TNRCC Surface Water Quality Monitoring Procedures Manual (1999).Laboratory analysis of samples was conducted by an outside contract lab, A & B Laboratories.Other than bacteriological samples, analysis for illicit discharge detection and source identification often consisted of field test kits.
HCSWQS estimated that about 1,000 labor hours have been spent in this study for site reconnaissance, instream monitoring, discharge detection, source tracking, training, and meetings. About one third of the time was used for instream monitoring.
3.1.2Dry Weather Discharges from Stormwater System
Following at least 48hours of antecedent dry period, investigators walked along the banks of the subject streams and any flowing tributaries of the streams.Each discharge into the stream or tributary was sampled and sent to a local lab for enumeration of E. coli (EC).Field measurements of the each discharge were taken, which included a qualitative description (odor, clarity, presence of foam or sheen), discharge rate, pH, temperature, total chlorine, and conductivity.Illicit Discharge Detection teams investigated the length of Brickhouse Gully and Vogel Creek twice; i.e., two passes, separated by about 3 to 4 weeks in time.
3.1.3Wastewater Treatment Plants
The Willowood WWTP and the Sunset WWTP were sampled 15 times each and the Westway WWTP 14 times.Samples for EC enumeration were taken and total and free chlorine residual measured at the weir and at the outfall pipe to the receiving stream. However, the Westway WWTP had a submerged outfall preventing the collection of end-of-pipe samples.Chlorine residual was measured using HACH test kit CN-66.
3.1.4Instream Samples
Base-flow was sampled after a minimum of 3days antecedent dry period.Frequency of sampling averaged once per week.Field parameters taken were pH, dissolved oxygen (DO), temperature, and conductivity.Laboratory analysis was performed for fecal coliform (FC), Escherichia coli (EC), total suspended solids (TSS), total dissolved solids (TDS), ammonia (NH3-N), and sulfates.Split samples were taken once per month for all parameters except for bacteria (EC and FC).HCSWQS observed a persistent algal bloom beginning in May, 2006 in Brickhouse Gully, and nutrient sampling was added to the original suite of parameters for Brickhouse Gully and Vogel Creek.These additional parameters included total Kjeldahl nitrogen (TKN), nitrate + nitrite (NO3+NO2-N), total phosphorus, ortho-phosphates, and chlorophyll a.
The City of Houston historical data at the Brickhouse Gully sampling site provided the baseline for this stream. There is no known historical baseline water quality data for the study reach of Vogel Creek.HCSWQS sampled the site at Breen Drive 17 times in order to establish a baseline.
Once high bacteria sources were eliminated to the extent practical, 21 and 17 instream water samples were taken at the Brickhouse Gully site and Vogel Creek site, respectively, in order to assess the effects that the high bacteria source elimination might have had on instream water quality.